Blackmail is an age-old art of convincing someone to do something they don't want to do based on information you have on them. Hopefully you'll never need to actually blackmail someone, but creating a file filled with nefarious deeds is easy to do.

Just for a little context here—this is one of those evil week posts where you have to fight evil with evil. I've learned this the hard way as one of my friends has been collecting what amounts to a blackmail folder on all of his friends he lovingly calls "The File."

We could run around in circles all day on why I'm still friends with this person—but the truth is, he's still a nice guy, and while the blackmail file is certainly annoying (and embarrassing), it's mostly in good fun, rather than something that will ruin all our lives. Chances are "The File" will never see the light of day. Still, in order to fight against this, I had to figure out how to catalog a collection of my own blackmail material. Here's what I've learned.

Document Everything That Happens with Your Smartphone

The first rule of collecting a blackmail file is to record everything that happens. This means having your phone at the ready in any situation that could be potentially embarrassing, including bars, restaurants, amusement parks, meetings, work, or snowy (and preferably icy) days.

From there, you simply need to be vigilant in capturing what happens. With video that's tough, but you can record audio from your pocket without them ever noticing.

For photos, you have to get a little more sneaky. You can either pretend like you're not taking a picture (remember on iPhone's the volume knob can be used to snap a picture, as can the volume clicker on the headphones), or download a tweak like SlyCam that stuffs a hidden camera toggle into the iPhone Notification Center.

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Back Up Your Evidence in Several Places

The most logical place your should take all your embarrassing files is a computer. Back up those photos, videos, and recordings on your computer, as well as in whatever cloud storage service you prefer.

We're big fans of Dropbox for a few reasons, but one of the best features of the service is that it automatically backs up your photos on Windows, Mac, iOS, and Android (Google+ also offers this on Android). This means when you take a photo on your phone, it automatically is saved online. It also means if your friend demands that you delete a picture from your phone, you can do so while still retaining a copy of the file.

The last step is to create triggers for other people's photos whenever possible. One way to do this if they use Instagram is with IFFTT's "New photo by specific user" filter. Every time your friend (or enemy) takes a photo, you can send that directly to Dropbox for safe keeping. This is only handy if they're likely to take dumb photos and delete them after thinking about it, but it's a good backup nonetheless.

We've also covered a few ways to do this for various other services so you can attempt to automate the grabbing of any embarrassing photos of your subject regardless of where they're taken. It's not perfect, but you'll be able to snatch pictures you "like" on Facebook or Instagram automatically, as well as by using a bookmarklet for random pictures on Facebook.

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Create a Backup Plan to Release the Files In Case Something Happens to You

Finally, as anyone who has seen a crime thriller knows, any good blackmail stash has a backup plan in case something happens to you. This means if you are incapable of releasing the documents on your own, they're automatically sent to friends, bosses, or newspapers.

To do this, you can use any number of services, but we like the online will PassMyWill because it's automated. PassMyWill combs your Facebook and Twitter feeds, and if you don't update for a while, it sends you an email. If you don't reply, it assumes you've passed away, and sends out passwords to your trusted associates. Other services like Legacy Locker do a similar thing, but require that a trusted individual verify your death before they're given access.

Either way, make sure you choose someone who can handle your blackmail file properly, and if need be, is willing to release those documents if necessary.

A Few Preventative Measures to Keep from Being Embarrassed Yourself

With this type of "light blackmail," the real worry is that these embarrassing photos, videos, or audio clips might eventually hit the internet. While you can't exactly keep that from happening on something like Youtube, you can at least least lock down your privacy settings on Facebook so you're not tagged in photos.

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Just jump into your privacy settings, click "Edit Settings" on the Timeline and Tagging section, and change "Who can see posts you've been tagged in on your timeline?" to "Only Me." The photo will still show up on your friends (or enemies) profile, but at least your family won't see it. It's also worth changing "Who can see what others post on your timeline?" to "Only Me" as well, just in case they try to post it on your timeline.

Unfortunately, that's really all you can do—but if you have your own set of blackmail documents, the chances of your arch-nemesis/friend releasing yours are pretty slim. Just make sure they know you have no qualms releasing those documents if need be.

As for the actual blackmail part, we're sure you can figure that out on your own, but hopefully it will never come to that. My process is essentially mutually assured destruction, but it's better than nothing.

This post is part of our Evil Week series at Lifehacker, where we look at the dark side of getting things done. Knowing evil means knowing how to beat it, so you can use your sinister powers for good. Want more? Check out our evil week tag page.